Rejecting offer after accepting

Hey peeps.. need some advice! Been searching for a job for 5 mths ever since I was laid off. Luck has been on my side recently and I got one offer with a fintech co.. Currently we are discussing comps package. On the other hand, I’ve completed interviews process with another great co - a multimedia tech giant. This co is highly selective and has tough interview process, recruiter mentioned it’s only down to me and another guy now. Honestly I really really like the 2nd co.. however it’s a question mark if I’ll be offered eventually. My qns: 1) do I accept offer with 1st co, then withdraw later as long as I hasn’t started? Very scare I’ll burn bridges as 1st co was referred by my ex-boss 2) reject 1st co and place all my bets on 2nd co I do not think 2nd co will come back within next week - they have notoriously long hiring process for senior hires (I had interviewed with them for 5 mths!). I need some advice on how to manage this situation! 🙏🏼 —————— Update as of 26 Sept: So I used the tactic of negotiating a higher package from co 1, thinking they might need a few days to come back BUT they accepted my proposal so now I have a better package compared to initial one. 😶 So I said ok and get them to generate the offer letter, likely will receive early next week.. Meanwhile I had a coffee chat with the HM from co 2 ytd, she said everything is positive for me that’s why she wanted to see me in person (she’s based in another country and happen to be in my country for a meeting).. my hunch is the offer is coming. I did dropped an email to the recruiter from co 2 to chase up the process.. -——————————— Update as of 30 Sept: Verbal offer from 2nd co is in.. offer letter from 1st co is in as well… 🫠